Make == for associative arrays test for equality, not identity. _aaEq was added to runtime/internal/aaA.d which forwards to TypeInfo_AssociativeArray.equals in genobj.d. On the codegen side, DtoAAEquals was added to gen/aa.cpp and is called from EqualExp::toElem in gen/toir.cpp. I assume that the frontend will produce an error if == is used on associative arrays of different type. This fixes DMD bug 1429.

module bug77;
import tango.stdc.string;
void main()
{
    size_t len;
    void func2()
    {
        char* prefix = "";

        void func()
        {
        len = strlen(prefix);
        assert(len == 0);
        }

        func();
    }
    func2();
}